Systems and methods for regulating fluid infusion in a patient

ABSTRACT

Closed-loop systems and methods are described herein for regulating a flow of medication being intermittently infused to a patient based on one or more vital signs. The dosage rate of the medication can be adjusted periodically as needed to ensure the patient&#39;s vital sign remains with a target range. Various safeguards can be used to ensure the safety and efficacy of the closed-loop systems and methods.

This application claims priority to U.S. provisional application havingSer. No. 63/199,034 filed on Dec. 3, 2020. This and all other referencedextrinsic materials are incorporated herein by reference in theirentirety. Where a definition or use of a term in a reference that isincorporated by reference is inconsistent or contrary to the definitionof that term provided herein, the definition of that term providedherein is deemed to be controlling.

FIELD OF THE INVENTION

The field of the invention is closed-loop fluid infusion systems andmethods, and in particular, systems and methods for use with intravenousfluid infusion pumps.

BACKGROUND

The following description includes information that may be useful inunderstanding the present invention. It is not an admission that any ofthe information provided herein is prior art or relevant to thepresently claimed invention, or that any publication specifically orimplicitly referenced is prior art.

Maintaining a patient's blood pressure or other vitals can be difficult,and poor control can affect the patient's wellbeing. During operations,low blood pressure can occur frequently and has been correlated tonegatively affect patient outcomes. For example, patients having a meanarterial pressure (MAP) less than 55-65 mmHg for just one minute duringan operation have a higher risk of death than those whose blood pressureremains stable.

Unfortunately, manual control of medication to maintain blood pressureand other vitals during surgery can be challenging. Optimization ofblood pressure or other vitals requires taking repeated measurements ofa patient's vital sign, and making frequent, manual adjustments ofmedication dosage rates. As this most typically requires continuousattention of a medical professional, this can be cost prohibitive anddifficult to achieve.

FIG. 1 illustrates a typical workflow for manually maintaining apatient's vital sign. A nurse or other medical professional reviews thepatient's vital sign such as on a monitor and then manually adjusts adosage rate of the medication to the patient. As medical professionalsoften care for multiple patients at a time, each patient's vital signsare checked periodically but not frequently, which misses theopportunity for additional corrections. In addition, the adjustments canbe arbitrary based on snapshot views of the patient's vital sign.

For blood pressure, such manual control often leads to the patient beingoutside of the target range for the patient for a significant amount oftime. For example, one study found that manual control of blood pressureresulted in patients being outside of the target range more than 50% ofthe time, with the patients being in hypotension (below the targetrange) 10%-15% of the time and in hypertension (above the target range)30%-40% of the time.

All publications identified herein are incorporated by reference to thesame extent as if each individual publication or patent application werespecifically and individually indicated to be incorporated by reference.Where a definition or use of a term in an incorporated reference isinconsistent or contrary to the definition of that term provided herein,the definition of that term provided herein applies and the definitionof that term in the reference does not apply.

Thus, there is still a need for closed-loop systems and methods forcontinuous optimization of the dose rate of a medication given to apatient over time.

SUMMARY OF THE INVENTION

The inventive subject matter provides apparatus, systems and methods forregulating a flow of medication or other fluid to a patient. Informationabout a patient such as one or more vital signs can be received from atleast one source including, for example, a transducer or other sensor. Atarget value and/or range for one or more of the vital signs can bereceived. In one example, the target value and/or range can be inputtedusing a graphical user interface. An initial dosage rate of themedication or other fluid to be administered to the patient can also bereceived.

Such vital signs could include, for example, a mean arterial pressure ofa patient, but could also comprise any other vital sign that can becontrolled through intermittent infusion of the medication, such as byusing an intravenous infusion device.

Based on information received about the patient, such as the one or morevital signs, a first control algorithm can be used to generate a reviseddosage rate for delivery of the medication or other fluid to thepatient. The first control algorithm determines a differential value bycomparing a value of the first vital sign with the target value, andthen generating the revised dosage rate as a function of the initial(first) or current dosage rate and the differential value. Oncegenerated, medication can then be delivered to the patient according tothe revised dosage rate. The first control algorithm can be configuredto continually monitor the patient's information (e.g., one or morevital signs), and make on-going corrections to the dosage rate of themedication or other fluid as needed to keep the patient's vital signwithin a target range (i.e., a predetermined range from the target valueof the vital sign).

In another embodiment, a non-transitory computer readable medium storesa computer program that includes commands to cause a processor toperform a method for regulating a flow of medication to a patient. Theprogram can receive information concerning (i) a first vital sign of thepatient from a first source and (ii) a target value for the first vitalsign. An initial or current dosage rate of a medication administered tothe patient can also be received.

The processor can run the computer program and compare a current valueof the first vital sign to the target value or range to determine adifferential value, and then generate a revised dosage rate for deliveryof the medication to the patient as a function of the initial (first) orcurrent dosage rate and the differential value. Once generated, themedication can be delivered to the patient according to the reviseddosage rate.

Various objects, features, aspects and advantages of the inventivesubject matter will become more apparent from the following detaileddescription of preferred embodiments, along with the accompanyingdrawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a prior art flow chart for manual regulation of apatient's vital sign.

FIG. 2 illustrates a flow chart for automatic regulation of a patient'svital sign.

FIG. 3 illustrates a diagram of one embodiment of a method forregulating a flow of medication to a patient.

FIG. 4 illustrates an exemplary embodiment of a first control algorithm.

FIG. 5 illustrates an exemplary embodiment of a rules engine.

FIG. 6 illustrates an example comparing a time in target of a patientusing manual control versus automated control.

FIG. 7 illustrates one embodiment of a system for automatic regulationof a patient's vital sign.

DETAILED DESCRIPTION

Throughout the following discussion, numerous references may be maderegarding servers, services, interfaces, portals, platforms, or othersystems formed from computing devices. It should be appreciated that theuse of such terms is deemed to represent one or more computing deviceshaving at least one processor configured to execute softwareinstructions stored on a computer readable tangible, non-transitorymedium. For example, a server can include one or more computersoperating as a web server, database server, or other type of computerserver in a manner to fulfill described roles, responsibilities, orfunctions.

The following discussion provides many example embodiments of theinventive subject matter. Although each embodiment represents a singlecombination of inventive elements, the inventive subject matter isconsidered to include all possible combinations of the disclosedelements. Thus if one embodiment comprises elements A, B, and C, and asecond embodiment comprises elements B and D, then the inventive subjectmatter is also considered to include other remaining combinations of A,B, C, or D, even if not explicitly disclosed.

FIG. 2 illustrates a simplified flowchart for automatic regulation of avital sign of a patient using automated adjustments of a dosage rate ofa medication to the patient based on changes to the patient's one ormore vital signs being monitored.

FIG. 3 illustrates a first embodiment of a method 100 for regulating aflow of medication 122 to a patient 114. A target value for a firstvital sign and an initial (first) or current dosage rate of a medication122 to be administered to a patient 114 can be received, such as via aninput to a graphical user interface 116.

Information 112 concerning the first vital sign of the patient 114 canbe received from a first source 110 directly such as from the sensor orindirectly such as from a patient monitoring device. Based on thereceived information 112, a revised dosage rate 118 can be generatedusing a first control algorithm. The medication 122 can then bedelivered to the patient 114 according to the revised dosage rate suchas with an infusion pump 120. In this manner, the first vital sign ofthe patient 114 can be periodically and continuously monitored andadjustments to the dosage rate of the medication 122 can be madedepending on the difference between the first vital sign and the targetvalue or range as well as other factors. In some embodiments, theadjustment to the dosage rate may consider the initial (first) orcurrent dosage rate, a differential value between the current vital signand the target value or range, and a scalar rate associated with themedication 122. Although a vasopressor is shown as the medication, it iscontemplated that the systems and methods described herein can be usedwith any other medications that can be used to control one or morevitals of a patient and are intermittently infused to a patient.

In some contemplated embodiments, a processor runs the first controlalgorithm which compares a value of the patient's first vital sign withthe target value or range to determine a differential value, and thengenerates the revised dosage rate as a function of the initial (first)or current dosage rate and the differential value.

As one example, it is contemplated that the systems and methods hereincan be used to regulate a blood pressure of a patient, such as bycontrolling a dosage rate of a vasopressor intermittently administeredto the patient. In such embodiments, it is contemplated that the firstvital sign may comprise a mean arterial pressure (MAP) of the patient,which could be measured using a transducer attached to the patient. Thesystems and methods are preferably configured to monitor and track theMAP of the patient, and utilize the first control algorithm to generaterevised dosage rates in response to changes in the MAP of the patient tothereby maintain the first vital sign of the patient within a targetrange of the of the target value (e.g., within 5 mmHg). The reviseddosage rate can be transmitted to an IV infusion device, for example,which can then change the dosage rate of the medication beingadministered to the patient.

It is further contemplated that additional safeguards can be used tohelp ensure the systems and methods described herein are not concealingthat a patient's condition is worsening by maintaining the patient'sblood pressure or other vital sign such as by continuing to increase thedosage rate of the medication. In one such example, it is contemplatedthat the initial (first) dosage rate, a set of prior dosage rates, acurrent dosage rate (if applicable), and the revised dosage rate can bestored in a memory communicatively coupled with the processor, and theset of stored dosage rates of the medication for the patient can beanalyzed by the processor. If a rate of change of the dosage rate of themedication over a set time period exceeds a predetermined threshold, analarm command can be generated to notify the medical team of thepotential worsening condition of the patient despite the patient's vitalsign remaining in the target range.

Additionally, or alternatively, another safeguard that can be used is torequire that a set time period has elapsed between dosage rate changesbefore making further adjustments to the dosage rate of the medication.For example, it is contemplated that in the step of generating therevised dosage rate, a first time period is determined that is measuredas the time elapsed since the last dosage rate change of the medication.Then, if the first time period is less than a minimum time period, thedosage rate is not changed. However, if the first time period is greaterthan or equal to the minimum time period, the revised dosage rate can beset as the initial (first) or current dosage rate of the medication forthe patient.

In such embodiments, it is preferred that the minimum time period isgreater than or equal to a line lag of the medication being delivered,which can be calculated by understanding the length of tubing throughwhich the medication must flow from the medication source to thepatient, and the flow rate of the medication through the tubing. Generalestimations can also work. It is important that the systems and methodsdo not alter the dosage rate until the patient is actually receivingmedication at the prior dosage rate. Because the line lag can be one totwo minutes or more depending on the circumstances, this safeguard helpsensure that the systems and methods do not overcompensate by adjustingthe dosage rate of the medication without accounting for the line lagbut instead allow time for the change in dosage rate to take effect.

To further ensure the closed-loop systems and methods are safe for thepatient, it is preferred that minimum and maximum dosage rates of themedication are inputted for the patient. Where this has not occurred, itis contemplated that the systems and methods could prompt the medicalprofessional for the information or could have default values that couldbe used that may depend on the medication being delivered to thepatient.

In such embodiments, it is contemplated that the first control algorithmcan further determine whether the revised dosage rate is greater thanthe minimum dosage rate and less than the maximum dosage rate. If not,it is contemplated that the initial (first) or current dosage rate canbe maintained (not adjusted) and the medication can be delivered to thepatient according to the initial (first) or current dosage rate. In suchinstances, it is further contemplated that an alarm status can begenerated to alert the medical professional to the issue. Alternatively,it is contemplated that the revised dosage rate could be adjusted fromthe current dosage rate to the minimum or maximum dosage rate, asapplicable, and the alarm status can be generated.

In still further embodiments, it is contemplated that the systems andmethods can further ensure that the dosage rate is not changed by morethan a set amount (limit change threshold) at any one adjustment. Forexample, it is contemplated that the first control algorithm cancalculate a difference between the revised dosage rate and the initial(first) or current dosage rate prior to delivering the medication to thepatient according to the revised dosage rate. If the difference betweenthe two dosage rates exceeds the limit change threshold, the reviseddosage rate can instead be set to the limit change threshold plus theinitial (first) or current dosage rate. Thus, in such embodiments, whilethe dosage rate will be changed, it will only be adjusted by the valueof the limit change threshold. In such instances, it is furthercontemplated that an alarm status could be generated to alert themedical professional to the issue.

It is further contemplated that the first vital sign could beindependently monitored from a second source in addition to the firstsource. Information about the first vital sign can be received from thesecond source and the received information from the second source can becompared with information received about the first vital sign from thefirst source. If the difference between the information of the first andsecond sources exceeds a predetermined threshold, an alarm command canbe generated. Whether the units of the measured vital sign are differentbetween that measured by the first and second sources, it iscontemplated that the received information from one of the sources canbe converted to allow a comparison of the values. For example, for bloodpressure monitoring, it is contemplated that a first source couldmonitoring the MAP of the patient while the second source could monitorthe systolic blood pressure (SBP) and diastolic blood pressure (DBP) ofthe patient. In such circumstances, the systolic blood pressure could beconverted to MAP using the following equation:

${MAP} = \frac{{SBP} + {2*({DBP})}}{3}$

In addition to the first vital sign, it is contemplated that other vitalsigns of the patient could be monitored including, for example, oxygensaturation levels (SpO₂), body temperature, and electrical signals fromthe heart (EKG). Additionally, or alternatively, perfusion and/ormetabolic activity in the patient could also be monitored.

As but one example, in the case of monitoring a blood pressure of thepatient, it is contemplated that the first source can be a transducerattached to the patient and the second source could be a blood pressuremonitor configured to monitor a systolic blood pressure.

In another aspect, a non-transitory computer readable medium is providedin which a computer program is stored. Preferably, the computer programincludes commands that cause a processor of a server to perform a methodfor regulating a flow of medication to a patient. Thus, for example, anintravenous infusion device can comprise a processor communicativelycoupled with the non-transitory computer readable medium where thecomputer program is stored, which may include or comprise the firstcontrol algorithm discussed above. The intravenous infusion device couldbe a control unit to monitor and calculate dosage rates or a separatecontrol unit could communicate with the intravenous infusion device tocontrol the dosage rate of a medication to the patient.

The computer program can be configured to receive, via the control unit,information concerning a first vital sign of a patient from a firstsource. A target value of the first vital sign and an initial (first) orcurrent dosage rate of a medication to be or being administered to thepatient can also be received, such as via a GUI connected to the controlunit.

Based on the information received, the processor of the control unit canrun the computer program and compare a value of the first vital signwith the target value or range to determine a differential value. Arevised dosage rate can then be generated and transmitted to theinfusion device for delivery of the medication to the patient based onthe initial (first) or current dosage rate and the differential value,and the current dosage rate and can be adjusted to the revised dosagerate.

The medication can then be delivered to the patient according to therevised dosage rate using the infusion device.

In some embodiments, it is contemplated that the first vital sign cancomprise a mean arterial pressure of the patient, and the medication cancomprise a vasopressor. In such embodiments, it is contemplated that thefirst source can be a transducer attached to the patient or anothersensor capable of measuring MAP or other indicator of the blood pressureof the patient.

The first dosage rate, prior dosage rates, a current dosage rate ifapplicable, and the revised dosage rate can be stored in the same ordifferent non-transitory computer readable medium. A set of the storeddosage rates of the medication can be analyzed and an alarm command canbe generated if a rate of change of the dosage rates over a specifictime period exceeds a predetermined threshold.

As discussed above, various other safeguards can be implemented in thecomputer program to ensure that the adjustments to the dosage rate issafe for the patient. Examples include setting minimum and maximumdosage rates of the medication, limiting how frequently dosage rates canbe adjusted, and/or setting a maximum value for a single adjustment tothe dosage rate.

Thus, for example, it is contemplated that generating the revised dosagerate includes first determining whether at least a preset amount of timeor minimum time period has elapsed since the last dosage rate change,and if not, the dosage rate can remain unchanged. If the amount ofelapsed time exceeds the minimum time period, the dosage rate can beadjusted. Preferably, in such embodiments, the minimum time period canbe greater or equal to a line lag that exists for the medication beingadministered to the patient. As discussed above, this line lag is basedon a length of the tubing as measured from the medication source to thepatient and a flow rate of the medication through the tubing.

It is also contemplated that generating the revised dosage rate couldinclude calculating a difference between the revised dosage rate and theinitial (first) or current dosage rate. If the difference between thecurrent and revised dosage rates exceeds a limit change threshold, therevised dosage rate can be set to the limit change threshold plus theinitial (first) or current dosage rate.

Various systems are also contemplated for regulating a flow ofmedication to a patient. In FIG. 7, one embodiment of a system 200 cancomprise a control unit 220 having a processor 222 communicativelycoupled with a memory 224 that is configured to store a first controlalgorithm. The control unit 220 is configured to receive informationconcerning a first vital sign of a patient 240 from a first source, atarget value or range for the first vital sign, and an initial (first)or current dosage rate for intermittent delivery of the medication tothe patient. The medication can be delivered using an infusion devicewhich may or may not comprise the control unit 220.

If the vital sign is outside of the target range, the control unit 220generates a revised dosage rate for delivery of the medication to thepatient 240 using the first control algorithm. The first controlalgorithm is programmed to compare a value of the first vital sign withthe target value or range to determine a differential value, and thengenerate the revised dosage rate based on the initial (first) or currentdosage rate and the differential value. For example, if the patient'svital sign exceeds the target value or range, the difference between thevital sign and the target value or range can be calculated (thedifferential). The control unit can then calculate the additional amountof medicine (increase to the dosage rate) needed to reduce the vitalsign to be within the target range. This increase to the dosage rate canthen be added to the current dosage rate to generate the revised dosagerate.

The control unit 220 can then send a command signal to cause themedication to be delivered via an infusion pump 230 to the patient 240at the revised dosage rate.

In some contemplated embodiments, the first vital sign comprises a meanarterial pressure of the patient 240 and the first source comprises atransducer attached to the patient 240.

It is also contemplated that the control unit 220 can store the initialdosage rate and a history of adjustments to the dosage rate or reviseddosage rates, and analyze the stored dosage rates of the medication forthe patient 240. If a rate of change of the dosage rates over a certaintime period exceeds a predetermined threshold, the control unit 220 cangenerate an alarm command.

As discussed above, various other safeguards can be implemented in thecontrol unit 220 control algorithm to ensure that the dosage rate aresafe for the patient 240. Examples include setting minimum and maximumdosage rates, limiting how frequently dosage rates are adjusted, and/orsetting a maximum value for dosage rate adjustments.

An exemplary embodiment of the computer software or first controlalgorithm is shown in FIG. 4. A PID controller can be used to determinea dosage rate change based on the target value for the vital sign, thecurrent value of the vital sign, and optionally a blood pressure historyof the patient. The resulting value can be multiplied by a drug scalarto arrive at the dosage rate change value which can then be combinedwith the current dosage rate to generate a revised dosage rate. Therevised dosage rate can be analyzed by a rules engine to ensure thesafety of the new dosage rate for the patient, such as by implementingsome or all of the safeguards described above.

An exemplary rules engine is shown in FIG. 5. As shown, the reviseddosage rate calculated using the control algorithm can be analyzed toensure it is safe for the patient. Although shown in a specific order,it is contemplated that the order of the analyses can be varied withoutdeparting from the scope of the invention.

As shown, an elapsed time since the last dosage rate change of themedication can be monitored. When a revised dosage rate is calculated,the elapsed time can be compared with a first threshold. If the elapsedtime is less than the first threshold, the dosage rate will not beadjusted (no change). If the elapsed time is greater than or equal tothe first threshold, the dosage rate will be adjusted if all otherprogrammed criteria are met.

the adjustment to the dosage rate can also be analyzed to ensure theadjustment is greater than a minimum value and less than a maximumvalue. This helps ensure that the adjustment is not made unless over aminimum amount such as a minimum change permitted by the infusiondevice. It also ensures that any adjustments to the dosage rate aregradual steps rather than a large change over a short time period. Ifthe adjustment is between the two values, the dosage rate will beadjusted if all other programmed criteria are met. If not, the dosagerate will not be adjusted (no change).

The revised dosage rate may also be compared with minimum and maximumdosage rate values to ensure the revised dosage rate does not falloutside of these thresholds. If the revised dosage rate is between thetwo values, the dosage rate will be adjusted if all other programmedcriteria are met. If not, the dosage rate will not be adjusted (nochange).

FIG. 6 illustrates a comparison of manual control of a blood pressure ofa patient to automated control using the closed-loop systems and methodsdescribed herein. As shown, the time in target of the automated control(95%) greatly exceeded the time in target of the manual control (46% and59%). The time in target is calculated by determining how long thepatient's blood pressure was within ±5 mmHg of the set target value forthe patient over a specified time period.

The use of the closed-loop systems and methods described herein alsoresulted in a total dose of vasopressor in those patients using theclosed-loop systems and methods being 40% lower than those patientsusing manual control (control group). In addition, the closed-loopsystem adjusted dosage rates of the vasopressor more than 1,000 timesper patient compared with a median of 15 times per patient in thecontrol group.

The percentage of intraoperative case time a patient had hypotension(defined as a MAP <90% of the patient's baseline MAP) was 1.2% for thoseusing the closed-loop systems and methods and 21.5% for those usingmanual control. The percentage of intraoperative case time with a MAP<65 mmHg was also lower for those using the closed-loop system than inthe control group (average of 0% vs 1.9%). Patients using theclosed-loop systems and methods were also within their target MAP range(±10 mmHg of their baseline MAP value) for an average of 97.2% of thetime compared with an average of 58.8% of the time for those undermanual control. The percentage of time with hypertension (defined as aMAP >10 mmHg of the MAP target) was also lower for those using theclosed-loop systems and methods than those in the control group usingmanual control (average of 2.5% vs 12.9%).

As used herein, and unless the context dictates otherwise, the term“coupled to” is intended to include both direct coupling (in which twoelements that are coupled to each other contact each other) and indirectcoupling (in which at least one additional element is located betweenthe two elements). Therefore, the terms “coupled to” and “coupled with”are used synonymously.

In some embodiments, the numbers expressing measurements, quantities ofingredients, properties such as concentration, reaction conditions, andso forth, used to describe and claim certain embodiments of theinvention are to be understood as being modified in some instances bythe term “about.” Accordingly, in some embodiments, the numericalparameters set forth in the written description and attached claims areapproximations that can vary depending upon the desired propertiessought to be obtained by a particular embodiment. In some embodiments,the numerical parameters should be construed in light of the number ofreported significant digits and by applying ordinary roundingtechniques. Notwithstanding that the numerical ranges and parameterssetting forth the broad scope of some embodiments of the invention areapproximations, the numerical values set forth in the specific examplesare reported as precisely as practicable. The numerical values presentedin some embodiments of the invention may contain certain errorsnecessarily resulting from the standard deviation found in theirrespective testing measurements.

Unless the context dictates the contrary, all ranges set forth hereinshould be interpreted as being inclusive of their endpoints andopen-ended ranges should be interpreted to include only commerciallypractical values. Similarly, all lists of values should be considered asinclusive of intermediate values unless the context indicates thecontrary.

As used in the description herein and throughout the claims that follow,the meaning of “a,” “an,” and “the” includes plural reference unless thecontext clearly dictates otherwise. Also, as used in the descriptionherein, the meaning of “in” includes “in” and “on” unless the contextclearly dictates otherwise.

The recitation of ranges of values herein is merely intended to serve asa shorthand method of referring individually to each separate valuefalling within the range. Unless otherwise indicated herein, eachindividual value with a range is incorporated into the specification asif it were individually recited herein. All methods described herein canbe performed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g. “such as”) provided with respectto certain embodiments herein is intended merely to better illuminatethe invention and does not pose a limitation on the scope of theinvention otherwise claimed. No language in the specification should beconstrued as indicating any non-claimed element essential to thepractice of the invention.

Groupings of alternative elements or embodiments of the inventiondisclosed herein are not to be construed as limitations. Each groupmember can be referred to and claimed individually or in any combinationwith other members of the group or other elements found herein. One ormore members of a group can be included in, or deleted from, a group forreasons of convenience and/or patentability. When any such inclusion ordeletion occurs, the specification is herein deemed to contain the groupas modified thus fulfilling the written description of all Markushgroups used in the appended claims.

It should be apparent to those skilled in the art that many moremodifications besides those already described are possible withoutdeparting from the inventive concepts herein. The inventive subjectmatter, therefore, is not to be restricted except in the spirit of theappended claims. Moreover, in interpreting both the specification andthe claims, all terms should be interpreted in the broadest possiblemanner consistent with the context. In particular, the terms “comprises”and “comprising” should be interpreted as referring to elements,components, or steps in a non-exclusive manner, indicating that thereferenced elements, components, or steps may be present, or utilized,or combined with other elements, components, or steps that are notexpressly referenced. Where the specification claims refers to at leastone of something selected from the group consisting of A, B, C . . . andN, the text should be interpreted as requiring only one element from thegroup, not A plus N, or B plus N, etc.

What is claimed is:
 1. A method for regulating a flow of medication to apatient, comprising: receiving information representing a current valueof a first vital sign of a patient from a first source; receiving atarget value or range for the first vital sign; receiving and storing afirst dosage rate of a medication administered to the patient; if theinformation representing the current value of the first vital sign fallsoutside of the target range, generating a revised dosage rate fordelivery of the medication to the patient using a first controlalgorithm, wherein the first control algorithm includes the followingsteps: comparing the information representing the current value of thefirst vital sign with the target value or range to determine adifferential value; calculating a dosage adjustment based on thedifferential value and a drug scalar value; and generating the reviseddosage rate as a function of the dosage adjustment and the first dosagerate; delivering the medication to the patient according to the reviseddosage rate; storing the revised dosage rate; analyzing a set of priordosage rates of the medication for the patient including the firstdosage rate; and generating an alarm command if a rate of change of theprior dosage rates over a set time period exceeds a predeterminedthreshold.
 2. The method of claim 1, wherein the first vital signcomprises a mean arterial pressure of the patient, and wherein the firstsource comprises a transducer attached to the patient.
 3. The method ofclaim 1, wherein the step of generating the revised dosage rate furthercomprises: prior to delivering the medication to the patient accordingto the revised dosage rate, determining whether a first time periodexceeds a minimum time period, wherein the first time period is definedas an elapsed time since a last dosage rate change occurred; if thefirst time period is less than the minimum time period, setting therevised dosage rate to the first dosage rate; if the first time periodis greater than the minimum time period, delivering the medication tothe patient according to the revised dosage rate; and wherein theminimum time period is greater or equal to a line lag.
 4. The method ofclaim 1, further comprising: receiving a minimum dosage rate and amaximum dosage rate; and wherein the first control algorithm furthercomprises: determining whether the revised dosage rate is greater thanthe minimum dosage rate and less than the maximum dosage rate; and ifnot, (i) setting the revised dosage rate to the first dosage rate, (ii)maintaining the first dosage rate and delivering the medication to thepatient according to the first dosage rate, and (iii) generating analarm status.
 5. The method of claim 1, wherein the first controlalgorithm further comprises: prior to delivering the medication to thepatient according to the revised dosage rate, calculating a differencebetween the revised dosage rate and the first dosage rate; and if thedifference exceeds a limit change threshold, setting the revised dosagerate to the limit change threshold plus the first dosage rate.
 6. Themethod of claim 1, further comprising: receiving information concerningthe first vital sign from a second source comprising a blood pressuremonitor configured to monitor a systolic blood pressure of the patient;comparing the information received concerning the first vital sign fromthe first and second sources; if the difference between the first vitalsign as measured from the first and second sources exceeds apredetermined threshold, generating an alarm command.
 7. The method ofclaim 1, wherein the medication comprises a vasopressor.
 8. The methodof claim 7, wherein the first vital sign comprises a mean arterialpressure of the patient, and wherein the first control algorithm isconfigured to generate the revised dosage rate to maintain the firstvital sign within 5 mmHg of the target value.
 9. The method of claim 1,further comprising: receiving a flow rate of a carrier fluid;calculating a line lag based on the flow rate of the carrier fluid;setting a minimum time period equal to the line lag; and wherein thestep of generating the revised dosage rate further comprises firstdetermining whether a first time period as measured as time elapsedsince a last dosage rate change exceeds the minimum time period.
 10. Anon-transitory computer readable medium in which a computer program isstored, wherein the computer program includes commands which cause aprocessor of a server to perform a method for regulating a flow ofmedication to a patient, the method comprising: receiving, via a controlunit, information representing a first vital sign of a patient from afirst source; receiving, via the control unit, a target value for thefirst vital sign; receiving, via the control unit, a first dosage rateof a medication administered to the patient and storing the first dosagerate; the control unit comparing a current value of the first vital signwith the target value to determine a differential value; generating, viathe control unit, a dosage adjustment based on the differential valueand a drug scalar value; generating, via the control unit, a reviseddosage rate for delivery of the medication to the patient as a functionof the first dosage rate and the dosage adjustment and using computerprogram; storing the revised dosage rate in the non-transitory computerreadable medium; analyzing a set of dosage rates of the medication forthe patient including the first dosage rate; generating an alarm commandif a rate of change of the dosage rates over a set time period exceeds apredetermined threshold; and delivering the medication to the patientaccording to the revised dosage rate.
 11. The non-transitory computerreadable medium of claim 10, wherein the first vital sign comprises amean arterial pressure of the patient, and wherein the first sourcecomprises a transducer attached to the patient.
 12. The non-transitorycomputer readable medium of claim 10, wherein the step of generating therevised dosage rate further comprises: prior to delivering themedication to the patient according to the revised dosage rate,determining whether a first time period exceeds a minimum time period,wherein the first time period is defined as an elapsed time since a lastdosage rate change occurred; if the first time period is less than theminimum time period, setting the revised dosage rate to the first dosagerate; if the first time period is greater than the minimum time period,delivering the medication to the patient according to the revised dosagerate; and wherein the minimum time period is greater or equal to a linelag.
 13. The non-transitory computer readable medium of claim 10,wherein the method further comprises: receiving a minimum dosage rateand storing the minimum dosage rate in the non-transitory computerreadable medium; receiving a maximum dosage rate and storing the maximumdosage rate in the non-transitory computer readable medium; anddetermining whether the revised dosage rate is greater than the minimumdosage rate and less than the maximum dosage rate; and if not, (i)setting the revised dosage rate to the first dosage rate, (ii)delivering the medication to the patient according to the first dosagerate, and (iii) generating an alarm command.
 14. The non-transitorycomputer readable medium of claim 10, wherein the method furthercomprises: prior to delivering the medication to the patient accordingto the revised dosage rate, calculating a difference between the reviseddosage rate and the first dosage rate; and if the difference exceeds alimit change threshold, setting the revised dosage rate to the limitchange threshold plus the first dosage rate.
 15. The non-transitorycomputer readable medium of claim 10, wherein the method furthercomprises: receiving information concerning the first vital sign from asecond source comprising a blood pressure monitor configured to monitora systolic blood pressure of the patient; comparing the informationreceived concerning the first vital sign from the first and secondsources; if the difference between the first vital sign as measured fromthe first and second sources exceeds a predetermined threshold,generating an alarm command.
 16. The non-transitory computer readablemedium of claim 10, wherein the medication comprises a vasopressor, andwherein the first vital sign comprises a mean arterial pressure of thepatient, and wherein the first control algorithm is configured togenerate the revised dosage rate to maintain the first vital sign within5 mmHg of the target value.
 17. The non-transitory computer readablemedium of claim 10, wherein the method further comprises: receiving aflow rate of a carrier fluid; calculating a line lag based on the flowrate of the carrier fluid; setting a minimum time period equal to theline lag; and wherein the step of generating the revised dosage ratefurther comprises first determining whether a first time period asmeasured as time elapsed since a last dosage rate change exceeds theminimum time period.
 18. A system for regulating a flow of medication toa patient, comprising: a control unit comprising a processor and amemory communicatively coupled with the processor, wherein the memorystores a first control algorithm; the control unit configured to receiveinformation concerning a first vital sign of a patient from a firstsource; the control unit further configured to receive a target value orrange for the first vital sign and a first dosage rate for delivery of amedication to the patient; the control unit generating a revised dosagerate for delivery of the medication to the patient using a first controlalgorithm; the control unit sending a command signal to cause themedication to be delivered to the patient at the revised dosage rate;wherein the first control algorithm comprises the following steps:comparing a current value of the first vital sign with the target valueor range to determine a differential value; calculating a dosageadjustment based on the differential value and a drug scalar value; andgenerating the revised dosage rate as a function of the dosageadjustment and the first dosage rate; and wherein the control unit isfurther configured to: store the first dosage rate and the reviseddosage rate; analyze a set of dosage rates of the medication for thepatient; and generate an alarm command if a rate of change of the dosagerates over a set time period exceeds a predetermined threshold.
 19. Thesystem of claim 18, wherein the first vital sign comprises a meanarterial pressure of the patient, and wherein the first source comprisesa transducer attached to the patient.
 20. The system of claim 18,wherein the control unit is further configured to generate the reviseddosage rate by: prior to delivering the medication to the patientaccording to the revised dosage rate, determining whether a first timeperiod exceeds a minimum time period, wherein the first time period isdefined as an elapsed time since a last dosage rate change occurred; andif the first time period is less than the minimum time period, settingthe revised dosage rate to the first dosage rate; if the first timeperiod is greater than the minimum time period, delivering themedication to the patient according to the revised dosage rate; andwherein the minimum time period is greater or equal to a line lag. 21.The system of claim 18, wherein the control unit is further configuredto: receive a minimum dosage rate and a maximum dosage rate; determinewhether the revised dosage rate is greater than the minimum dosage rateand less than the maximum dosage rate; and if not, (i) set the reviseddosage rate to the first dosage rate, (ii) maintain the first dosagerate and deliver the medication to the patient according to the firstdosage rate, and (iii) generate an alarm command.
 22. The system ofclaim 18, wherein the control unit is further configured to: calculate adifference between the revised dosage rate and the first dosage rateprior to delivering the medication to the patient according to therevised dosage rate; and if the difference exceeds a limit changethreshold, set the revised dosage rate to the limit change thresholdplus the first dosage rate.
 23. The system of claim 18, wherein thecontrol unit is further configured to: receive information concerningthe first vital sign from a second source comprising a blood pressuremonitor configured to monitor a systolic blood pressure of the patient;compare the information received concerning the first vital sign fromthe first and second sources; if the difference between the first vitalsign as measured from the first and second sources exceeds apredetermined threshold, generate an alarm command.
 24. The system ofclaim 18, wherein the medication comprises a vasopressor, and whereinthe first vital sign comprises a mean arterial pressure of the patient,and wherein the first control algorithm is configured to generate therevised dosage rate to maintain the first vital sign within 5 mmHg ofthe target value.
 25. The system of claim 18, wherein the control unitis further configured to: receive a flow rate of a carrier fluid;calculate a line lag based on the flow rate of the carrier fluid; set aminimum time period equal to the line lag; and wherein the step ofgenerating the revised dosage rate further comprises first determiningwhether a first time period as measured as time elapsed since a lastdosage rate change exceeds the minimum time period.
 26. The system ofclaim 18, wherein the control unit is further configured to: beforegenerating the revised dosage rate, compare the information concerning afirst vital sign to a stored vital sign representing the vital signprior to receiving the first vital sign; and if the first vital sign isequal to the stored vital sign, set the revised dosage rate to the firstdosage rate.